The present invention relates to a vehicle body front structure and, more particularly, to a vehicle body front structure which has a extension member rearwardly and downwardly inclined from a rear end of a front side member.
Japanese Patent Application Laid-Open Publication No. H10-119826 discloses a vehicle body front structure which, particularly, referring to FIG. 1 and associated description, has a structure that includes laterally spaced apart front side members extending in a fore and aft direction of a vehicle body, and extension members contiguous with rear ends of the front side members respectively, with the extension rear members being inclined rearward and downward along a dash panel and located beneath a floor panel.
However, upon careful studies undertaken by the inventor, with such a vehicle body front structure, when the front side members are applied with large load from a vehicle front due to frontal collisions, this load is delivered through the front side members and acts upon extension members that are inclined rearward and downward. Then, it is conceivable that bending moments occur in the extension members to cause the extension members to deform rearward about centers of the curved sections thereof, resulting in a tendency to cause the dash panel to move backward into a vehicle compartment.
For this reason, there is a need for conducting a study to minimize backward displacement of the dash panel resulting from load coming from the vehicle front.
One of measures for minimizing backward displacement of the dash panel is considered to include a technology to improve moment resistances on upper walls of the extension members.
But, in case where the extension members are placed beneath the floor panel and each of the extension members takes the form of a closed cross-sectional structure with its upper wall formed from the floor panel, a whole of the floor panel needs to have an increased thickness to enhance moment resistance, with resultant significant increase in weight.
To this end, if the extension members are located above the floor member, as far as the extension members concern, the upper walls of these components are able to have increased thickness without increasing the thickness of the floor panel.
However, although it is conceivable for the extension members to be formed in closed cross-sectional structures by cutting a sheet material, bending the same and jointing associated portions, in order for the upper walls to have the increased thickness, the extension members should entirely have the increased thickness, or the separate reinforcing plates should be jointed to only the upper walls, resulting in increase in weight and deterioration in assembling workability.
Therefore, the present invention has been completed upon such careful studies conducted by the present inventor and has an object to provide a vehicle body front structure that enables to restrict backward deformations of extension members resulting from load applied to a vehicle front without inducing excessive increase in weight and deterioration in assembling workability for thereby minimizing backward displacement of a dash section involving a dash panel.
To achieve the above object, in one aspect according to the present invention, a vehicle body front structure comprises: a front side member extending at a front portion of a vehicle body in a fore and aft direction of the vehicle body; a dash panel vertically extending in the vehicle body; an extension member connected to the front side member at a rear side thereof and extending along the dash panel to have a lower curved section rearwardly and downwardly inclined with respect to the vehicle body; a suspension member located below the front side member and having a rear end connected to the lower curved section of the extension member, an extension rear member located above a floor panel that extends in the fore and aft direction of the vehicle body and having a closed cross-sectional structure that extends in the fore and aft direction of the vehicle body; and a floor member connected to the extension member at a rear side of the lower curved section of the extension member, the floor member being located above the extension rear member to be superposed on and connected to the extension rear member while extending in the fore and aft direction of the vehicle body, and the floor member having an upper wall with increased thickness.
Stated another way, in anther aspect according to the present invention, a vehicle body front structure comprises: a front side member extending at a front portion of a vehicle body in a fore and aft direction of the vehicle body; a dash panel vertically extending in the vehicle body; an extension member connected to the front side member at a rear side thereof and extending along the dash panel to have a lower curved section rearwardly and downwardly inclined with respect to the vehicle body; a suspension member located below the front side member and having a rear end connected to the lower curved section of the extension member; an extension rear member located above a floor panel that extends in the fore and aft direction of the vehicle body and having a closed cross-sectional structure that extends in the fore and aft direction of the vehicle body; and a floor member connected to the extension member at a rear side of the lower curved section of the extension member, the floor member being located above the extension rear member to be superposed on and connected to the extension rear member while extending in the fore and aft direction of the vehicle body, and the floor member having means for receiving a force to be rearwardly applied with respect to the vehicle body resulting from a force rearwardly applied to the front side member and the suspension member with respect to the vehicle body.
Other and further features, advantages, and benefits of the present invention will become more apparent from the following description taken in conjunction with the following drawings.